1. The Field of the Invention
The presently preferred embodiment of the innovations described herein relates generally to bone screws. More specifically, the presently preferred embodiment relates to a pedicle screw.
2. The Relevant Technology
The human spine extends from the head to the tailbone, and made-up of bones known as vertebrae. The spine is one of the most important structures in the human body. It is strong but flexible, allowing a wide range of movements. Because the spine is so important for support and movement, a problem, e.g. back disorders, can disrupt even the simplest activities of life. Depending on the condition of the spine, a doctor may choose to use a posterior approach to treat the back disorder that includes the use of a pedicle screw system where a biocompatible screw commonly made of titanium is placed in the pedicle of the vertebrae to provide a base for a further support structure, for example
Unfortunately, pedicle screws are not without their inherent problems. Complications from the use of pedicle screws are common, which include loosening, breakage, damage to nearby joints, penetration of major blood vessels, and injuries to delicate neurological structures including nerve roots and the spinal cord. Of these complications, damage to the adjacent neurological structures is among the most debilitating, and difficult to manage. Technology has been introduced over the years in an attempt to decrease the risk of nerve damage associated with placement of pedicle screws, for example, U.S. Pat. No. 7,235,076, titled METHOD OF IMPROVING PEDICLE SCREW PLACEMENT IN SPINAL SURGERY issued Jun. 26, 2007, which describes the use of a determining size and trajectory of a pedicle screw through 3D imaging. The use of intraoperative fluoroscopy can reduce the incidence of misplaced screws, as can technology which utilizes computer guidance-based on preoperative CT scanning. Even with these techniques, the risk of injury to nerve roots from the use of pedicle screw fixation continues to plague the use of these devices.
Nerve root injuries can be devastating. Patients with nerves that have been damaged by poorly placed pedicle screws may fail to recover; leading to chronic and disabling pain. These patients have few treatment options, and often remain in pain for years, if not for their entire lives. The nerve roots may be injured either at the time of surgery, or injury may accumulate over time from the threads of the screws acting against the roots.
What is needed is a new and simple design for a pedicle screw that will greatly reduce, or eliminate, the damage to nerve roots when used by properly trained and qualified surgeons.